Mass. Gen. Laws ch. 65 § 33A
Taxes imposed by this chapter and by corresponding provisions of earlier laws shall be assessed and collected within ten years of the date of death of the decedent or, in the case of future interests, within ten years of the date that the right of possession or enjoyment of property accrues; provided, however, that written notice of such death or of such accrual has been given to the commissioner within five years of the date of such death or accrual. If notice is not given within such time, the commissioner's right to assess and collect any tax due shall continue until five years after the giving of such notice. Notice to the commissioner of the death of the decedent shall be conclusively presumed to have been given upon the date of filing with the commissioner the return required under section twenty-two. Where any question relative to the taxes imposed by this chapter is pending before any agency or court at the end of the above-stated period, the commissioner's right to assess and collect any tax due shall continue until one year after the final determination of such question.
Mass. Gen. Laws ch. 65, § 33A